• Title/Summary/Keyword: specific productivity

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Design for Warm Forming of a Mg El-cover Part Using a Ductile Fracture Criterion (연성파괴이론에 의한 마그네슘 합금 EL-cover 부품 온간 성형 공정 설계)

  • Kim, S.W.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.23 no.4
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    • pp.238-243
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    • 2014
  • Recently, magnesium alloys have been widely used in the automotive, aerospace and electronics industries with the advantages of high specific strength, excellent machinability, high electrical conductivity, and high thermal conductivity. Deep drawn magnesium alloys not only meet the demands environmentally and the need for lighter products, but also can lead to remarkably improved productivity and more rapid qualification of the product The current study reports on a failure prediction procedure using finite element modeling (FEM) and a ductile fracture criterion and applies this procedure to the design of a deep drawing process. Critical damage values were determined from a series of uniaxial tensile tests and FEM simulations. They were then expressed as a function of strain rate and temperature. Based on the plastic deformation histories obtained from the FEM analyses of the warm drawing process and the critical damage value curves, the initiation time and location of fracture were predicted. The proposed method was applied to the process design for fabrication of a Mg automotive compressor case and verified with experimental results. The final results indicate that a Mg case part 39% lighter than an Al die casting part can be produced without any defects.

A Study on Prediction for Top Bead Width using Radial Basis Function Network (방사형기저함수망을 이용한 표면 비드폭 예측에 관한 연구)

  • 손준식;김인주;김일수;김학형
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.170-174
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    • 2004
  • Despite the widespread use in the various manufacturing industries, the full automation of the robotic CO$_2$ welding has not yet been achieved partly because the mathematical model for the process parameters of a given welding task is not fully understood and quantified. Several mathematical models to control welding quality, productivity, microstructure and weld properties in arc welding processes have been studied. However, it is not an easy task to apply them to the various practical situations because the relationship between the process parameters and the bead geometry is non-linear and also they are usually dependent on the specific experimental results. Practically, it is difficult, but important to know how to establish a mathematical model that can predict the result of the actual welding process and how to select the optimum welding condition under a certain constraint. In this paper, an attempt has been made to develop an Radial basis function network model to predict the weld top-bead width as a function of key process parameters in the robotic CO$_2$ welding. and to compare the developed model and a simple neural network model using two different training algorithms in order to verify performance. of the developed model.

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Control of Glucose Concentration in a Fed-Batch Cultivation of Scutellaria baicalensis G. Plant Cells a Self-Organizing Fuzzy Logic Controller

  • Choi, Jeong-Woo;Cho, Jin-Man;Kim, Young-Kee;Park, Soo-Yong;Kim, Ik-Hwan
    • Journal of Microbiology and Biotechnology
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    • v.11 no.5
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    • pp.739-748
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    • 2001
  • A self-organizing fuzzy logic controller using a genetic algorithm is described, which controlled the glucose concentration for the enhancement of flavonoid production in a fed-batch cultivation of Scutellaria baicalensis G. plant cells. The substrate feeding strategy in a fed-batch culture was to increase the flavonoid production by using the proposed kinetic model. For the two-stage culture, the substrate feeding strategy consisted of a first period with 28 g/I of glucose to promote cell growth, followed by a second period with 5 g/I of glucose to promote flavonoid production. A simple fuzzy logic controller and the self-organizing fuzzy logic controller using a genetic algorithm was constructed to control the glucose concentration in a fed-batch culture. The designed fuzzy logic controllers were applied to maintain the glucose concentration at given set-points of the two-stage culture in fed-batch cultivation. The experimental results showed that the self-organizing fuzzy logic controller improved the controller\`s performance, compared with that of the simple fuzzy logic controller. The specific production yield and productivity of flavonoids in the two-stage culture were higher than those in the batch culture.

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Gut Health of Pigs: Challenge Models and Response Criteria with a Critical Analysis of the Effectiveness of Selected Feed Additives - A Review

  • Adewole, D.I.;Kim, I.H.;Nyachoti, C.M.
    • Asian-Australasian Journal of Animal Sciences
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    • v.29 no.7
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    • pp.909-924
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    • 2016
  • The gut is the largest organ that helps with the immune function. Gut health, especially in young pigs has a significant benefit to health and performance. In an attempt to maintain and enhance intestinal health in pigs and improve productivity in the absence of in-feed antibiotics, researchers have evaluated a wide range of feed additives. Some of these additives such as zinc oxide, copper sulphate, egg yolk antibodies, mannan-oligosaccharides and spray dried porcine plasma and their effectiveness are discussed in this review. One approach to evaluate the effectiveness of these additives in vivo is to use an appropriate disease challenge model. Over the years, researchers have used a number of challenge models which include the use of specific strains of enterotoxigenic Escherichia coli, bacteria lipopolysaccharide challenge, oral challenge with Salmonella enteric serotype Typhimurium, sanitation challenge, and Lawsonia intercellularis challenge. These challenge models together with the criteria used to evaluate the responses of the animals to them are also discussed in this review.

Anti-Obesity Drugs: A Current Research Insight

  • Son Eun-hwa;In San-Whan;Kim Byung-Oh;Pyo Suhkneung
    • Biomedical Science Letters
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    • v.11 no.2
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    • pp.89-101
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    • 2005
  • Obesity is increasing worldwide and has become a major health burden in Western societies affecting every third American and every fifth European. Obesity makes a major contribution to morbidity and mortality, predisposing individuals to cardiovascular disease and diabetes. Many new substances are currently being investigated for their usefulness in the pharmacotherapy of obesity. Most anti-obesity drugs can be divided into four groups: those that reduce food intake; those that alter metabolism; those that increase thermogenesis; and those that regulate hormone involved in feeding behavior. In this article we review these and other agents available in various countries for the treatment of obesity. Perhaps more importantly, we have focussed on areas of potential productivity in the future. Over the last 5 or so years, this impetus in obesity research has provided us with exciting new drugs targets involved in the regulation of feeding behavior and cellular mechanism involved in energy expenditure. Recent development in the quest for control of human obesity include the discovery of hormones, neuropeptides, receptors and transcription factors involved in feeding behavior, metabolic rate and adipocyte development. For developing new, perhaps even more specific pharmacological agents, further research is needed to understand the individual different genetic and physiological basis of obesity. It remains the hope of research scientists that in the not too distant future we shall see a new class of anti-obesity drugs arising logically from the molecular biology revolutions.

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Production of Erythromycin Using a Carrier-Spported Mycelial Growth in a Fluidized-Bed Bioreactor (균사 증식 담체를 이용한 유동층 생물반응기에서 Erythromycin의 생산)

  • 김성환;배신규김정희
    • KSBB Journal
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    • v.4 no.3
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    • pp.241-245
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    • 1989
  • A carriersupported mycelial growth of Sreptomyces erythreus was applied to erythromycin fermentation sistem using celite as a support material. Hyphal growth through the pore matrices of the materials showed anchorages and provided a stable biofilm growth. When the phospate concentration was limited to 0.8g corn steep liquor/L(corresponding to 40mg KH2PO4/L), the specific production rate of erythromycin was increased from 557$\mu$g/g-cell.hr under unlimited condition to 2, 898 $\mu$g/g-cell.hr. A fluidized-bed bioreactor was operated for erythromycin production by a repeated fed-batch mode. The control of free mycelial concentration and the extension of production phase were considered important to maintain the reactor productivity at a desired level. The erythromycin production under phosphate-limited condition could be maintained for at least 600hrs.

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Optimization of Culture Conditions for D-Ribose Production by Transketolase-Deficient Bacillus subtilis JY1

  • Park, Yong-Cheol;Seo, Jin-Ho
    • Journal of Microbiology and Biotechnology
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    • v.14 no.4
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    • pp.665-672
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    • 2004
  • D-Ribose is a five-carbon sugar used for the commercial synthesis of riboflavin, antiviral agents, and flavor enhancers. Batch fermentations with transketolase-deficient B. subtilis JY1 were carried out to optimize the production of D-ribose from xylose. The best results for the fermentation were obtained with a temperature of $37^{\circ}C$ and an initial pH of 7.0. Among various sugars and sugar alcohols tested, glucose and sucrose were found to be the most effective for both cell growth and D-ribose production. The addition of 15 g/l xylose and 15 g/l glucose improved the fermentation performance, presumably due to the adequate supply of ATP in the xylose metabolism from D-xylulose to D-xylulose-5-phosphate. A batch culture in a 3.7-1 jar fermentor with 14.9 g/l xylose and 13.1 g/l glucose resulted in 10.1 g/l D-ribose concentration with a yield of 0.62 g D-ribose/g sugar consumed, and 0.25 g/l-h of productivity. Furthermore, the sugar utilization profile, indicating the simultaneous consumption of xylose and glucose, and respiratory parameters for the glucose and sucrose media suggested that the transketolase-deficient B. subtilis JY1 lost the glucose-specific enzyme II of the phosphoenolpyruvate transferase system.

Development about Welding-process Automatic System on the department of Axle Casing Nut for Commercial Vehicle (상용차용 액셀 케이싱의 너트부 용접공정 자동화 시스템 개발)

  • Kim, Jae-Yeol;Yoo, Sin;Oh, Sung-Min;Jang, Jong-Hoon
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.810-814
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    • 1996
  • The purpose of this exclusive welding-machine process using the welding Torch-rotation form is to develop a mechanism which can solve the problem of twisted welding wires and cables. The technique was developed by revising the torch position and smooth controlling of both the formal and reverse rotation. Some of the advantages of using the Torch-rotation form over the Work-rotation technique are the practical uses of increased work space and link work with the automation system of the plant. Using this welding machine process, It is possible to design a specific tool in order to solve the implemental problem. And I produced a control plate which can manipulate the progress of the entire process at the work place. Even if another kind of axle casing's welding work is used this process can be utilized if the fixed tip and work is produced and changed. The development if this exclusive welding-machine could reduce the manpower of skilled welding labor and after considerable analysis, this machine was found to increase productivity and better quality product in comparison to the handmade product.

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Estimation of Community-Based Unused Biomass Generation (지역단위 미이용 바이오매스 발생량 추정)

  • Choi, Eun-Hee;Lee, Mun-Yong;Yoon, Young-Man;Kim, Chang-Hyun;Yoon, Sung-Yee
    • Korean Journal of Organic Agriculture
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    • v.20 no.4
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    • pp.447-458
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    • 2012
  • This study was carried out to evaluation of biomass generation mechanisms and to propose the estimation method of biomass generation. Agricultural by-product biomass is generated during crops cultivation and after harvest. However these are not uniformly generated yearly and these depending on the seasons. For planning of biomass utilization, accurate information of the biomass resources is needed, especially characteristic and productivity of biomass are necessary. Agricultural by-product biomass are generated in a wide area being scattered and it is one of the major reason why agricultural biomass utilization is not activated compared with other waste biomass. In this study, estimation and evaluation biomass generation is achieved in specific spatial and temporal boundary, A-city in Gyeongi-do and september to November respectively. Quantity and quality of by-product biomass show big difference depending on the crop species and cultivation periods and these difference bring up that accurate biomass estimation should be considered during planning of biomass utilization and technology selecting for biomass converting to energy and other forms.

Development of Expert System for Burr Formation in Face Milling (밀링가공시 버형성 예측을 위한 전문가 시스템 개발)

  • Ko, Sung-Lim;Kim, Young-Jin;Ko, Dae-Cheol;Han, Sang-U;Lee, Je-Yeol;Ahn, Yong-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.2
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    • pp.199-205
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    • 2001
  • Burr makes troubles on manufacturing process due to deburring cost, quality of products and productivity. This paper described the results of experimental study on the influence of the cutting parameters on the formation of exit burrs in face milling. Using the results of experimental study, burr types are classified and data bases are developed to predict burr formation result. From the CAD file for work geometry and the NC data for tool path, the exit angles are calculated at every edges. This program predicts the burr geometry at exit edges using the prediction algorithm and data bases which are developed experimentally. Simulation results on deformation strain and temperature are also available in specific 2-dimensional cutting conditions. Also algorithm which can determine the exit angle is proposed.

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